1. Field of the Invention
The invention generally relates to hard drives used with computer systems and more particularly to a method and apparatus for preventing access to the hard drive until a password is entered.
2. Description of the Related Art
The rising popularity of portable computers has corresponded to the extraordinary improvements in the field, as portable computer systems rapidly develop the capabilities and characteristics of desktop models. For example, LCD displays for portable computers have become more sophisticated and readable. Many portables now include floppy disk drives to allow improved versatility and capacity. Furthermore, hard disk units are becoming common, offering greater speed and capacity than floppy drives.
The integration of hard drives into portable computers provides the user with much greater memory than floppy disk drives. Hard drives offer considerably shorter access times to data and programs. Consequently, the information that is most important to the user is commonly stored on the hard drive where the user has ready access. Information on the hard disk, therefore, may be extremely confidential and valuable, and must be protected. Ordinarily, access to the system as a whole is protected by a password program that restricts access to those that enter a password.
Password programs commonly employ a power-on password stored in the computer's CMOS memory. When the computer system initially powers up and completes the self-test operations, the computer executes a power-on password program. The password is read from the CMOS and compared to the password entered by the user on the keyboard to determine whether the correct password has been given. If so, the user is allowed access to the system. If not, the system remains inaccessible until the correct password is entered. Many systems allow only a few attempts at entering a password, after which the system must be turned off and powered up again to make another attempt.
For conventional desktop models, password programs generally provide sufficient defense to unauthorized access. For portable computers, however, power-on password protection may not be enough. Unlike their desktop counterparts, portable computers are easily stolen. A portable computer may be equipped with power-on password protection, which will prevent unauthorized access to the information on the hard disk unit through the computer system, but the hard drive unit may be physically removed from the computer and installed in another system. Because the new system does not employ password protection, the hard drive becomes accessible to an unauthorized user, and the data vulnerable to theft and misuse.
To prevent unauthorized access of this sort, the data may be encrypted before it is placed on the hard disk. Encryption involves altering the standard data code into a secret code, which must be decoded when it is retrieved from memory before the data can be used. An unauthorized user may thus put the drive in another computer to gain access to the code on the hard disk, but the data will be meaningless if it is not decoded. Encryption, however, requires support hardware and software in the computer system to encode and decode the data. Encryption also reduces the computer system's performance due to the delay while the encryption mechanism encodes or decodes the data.